Transitional stages of thin air film entrapment in drop-pool impact events

Abstract

Abstract

The turbulent bubble break-up cascade. Part 1. Theoretical developments

“…As such, the generation of sub-Hinze-scale subgrid bubbles will have to be addressed separately in a manner that bypasses the cascade considered in this work (see e.g. Chan et al 2018aChan et al ,b, 2019Mirjalili et al 2018;Mirjalili & Mani 2020). It is envisioned that distinct subgrid-scale models for sub-Hinze-scale and super-Hinze-scale subgrid bubbles be combined in an additive fashion in order to account for this myriad of fragmentation mechanisms and cover more bases for modelling the formation and dynamics of subgrid bubbles.…”

“…These super-Hinze-scale bubbles have Weber numbers of the order of or larger than unity. Note that most sub-Hinze-scale bubbles with Weber numbers smaller than unity are expected to be formed by distinct fragmentation mechanisms (Deane & Stokes 2002;Kiger & Duncan 2012;Chan, Urzay & Moin 2018b;Mirjalili, Chan & Mani 2018;Mirjalili & Mani 2020). For this reason, sub-Hinze-scale bubbles are not considered in detail in this work.…”

The turbulent bubble break-up cascade. Part 2. Numerical simulations of breaking waves

“…2018 c , 2019; Mirjalili et al. 2018; Mirjalili & Mani 2020). As is discussed in § 3, the simulations of this work do not have numerical support for sub-Hinze-scale bubbles, and thus these bubbles are out of the scope of the current work.…”

“…A number of candidate mechanisms have been proposed for various bubble-size subranges and wave-breaking stages, including bubble break-up by turbulence (Kolmogorov 1949;Hinze 1955), air entrainment and microbubble formation due to plunging jets and drops (Deane & Stokes 2002;Kiger & Duncan 2012;Chan, Urzay & Moin 2018c;Mirjalili, Chan & Mani 2018;Chan et al 2019;Mirjalili & Mani 2020), buoyant degassing and dissolution (Garrett, Li & Farmer 2000) and intermittency in the energy dissipation rate (Garrett et al 2000;Gemmrich 2010), although this intermittency remains a topic of active investigation (Deane 2016;Deane et al 2016b). Note that microbubble formation due to plunging jets and drops may entail the direct generation of sub-Hinze-scale bubbles with subunity Weber numbers from larger air sheets and films, which may bypass the action of turbulent break-up (Deane & Stokes 2002;Chan et al 2018cChan et al , 2019Mirjalili et al 2018;Mirjalili & Mani 2020). As is discussed in § 3, the simulations of this work do not have numerical support for sub-Hinze-scale bubbles, and thus these bubbles are out of the scope of the current work.…”

“…A number of candidate mechanisms have been proposed for various bubble-size subranges and wave-breaking stages, including bubble break-up by turbulence (Kolmogorov 1949; Hinze 1955), air entrainment and microbubble formation due to plunging jets and drops (Deane & Stokes 2002; Kiger & Duncan 2012; Chan, Urzay & Moin 2018 c ; Mirjalili, Chan & Mani 2018; Chan et al. 2019; Mirjalili & Mani 2020), buoyant degassing and dissolution (Garrett, Li & Farmer 2000) and intermittency in the energy dissipation rate (Garrett et al. 2000; Gemmrich 2010), although this intermittency remains a topic of active investigation (Deane 2016; Deane et al.…”